1. Field of the Invention
The present invention relates to a robot for loading and unloading reels of metal wires for a tubular wire stranding machine adapted to manufacture cables from wires unwound from the reels, these wires being for example of steel.
2. Description of the Prior Art
The wire stranding machine may comprise a variable number of reels, for example twenty-six, disposed in cradles acting as a support, and these reels are unwound at the same time, so as to form at the output side of the machine a single cable. The latter is provided for industrial uses, for example in public works or the oil or mining industry, etc . . .
Such a machine must of necessity undergo frequent stoppages to permit the changing of one or more completely unwound reels. The stoppages are a function of the length of wire contained in each of the reels, which length differs in accordance with the diameter of the wire employed. Indeed, wires of different diameters are laid around a core wire. The diameter of the wire of several reels may be different so that the length of the wire is also different.
It will therefore be understood that this presents a problem for the operator supervising the operation of the wire stranding machine to foresee and carry out all these reel changes.
Further, all the operations for unloading the empty reel, loading the full reel and discharging the empty reel, etc . . . , and the monitoring operations have been carried out manually up to the present time.
The replacement of a empty reel is effected manually in the following manner:
The operator notices that a reel among those being unwound is almost completely unwound and he decides to stop the machine. The tubular stranding machine stops, the hood of the considered reel is opened so as to have access to the reel support cradle. The operator cuts the wire remaining on the reel to be changed and connects it to the substituted full reel. He manually opens the locking points or studs maintaining the reel on its support cradle. He extracts the empty reel by means of a pulley-block and conveys it to the discharging zone. He takes by means of the pulley-block a suitably chosen full reel whose characteristics are identical to those of the reel being changed, in a preparation bay. These bays are equal in number to the number of diameters of different wires in the cable being manufactured, for exemple six, which corresponds therefore to six different wires for twenty-six reels.
The operator transports the full reel to a support cradle and lowers it onto the latter. He closes the points whereby the reel is held in position on the cradle. He must then connect the wire of the new reel to the remaining wire of the previous reel, for example by welding the two ends of these wires. He closes the hood of the stranding machine and starts up the latter. On this type of machine, several reels of the same type must sometimes be replaced at the same time. The operations described hereinbefore must therefore be repeated for each reel to be replaced.
It will be understood that all these operations are both time continuing and costly, since they markedly reduce the productivity of the stranding machine, and are dangerous for the operators in charge of these operations and for the stranding machine.